java - 我不明白 Spring 中的 Autowired

Question

ApplicationContext

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans 
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context 
http://www.springframework.org/schema/context/spring-context-3.0.xsd">

<context:annotation-config />

    <bean id="beanFactory" class="testSpring.BeanFactory" />

    <bean id="a1" class="testSpring.A">
        <property name="name" value="I am A one!"></property>
    </bean>

    <bean id="a2" class="testSpring.A">
        <property name="name" value="I am A two!"></property>
    </bean>

    <bean id="b" class="testSpring.B">
        <property name="name" value="I am B!"></property>
    </bean>

</beans>

主要

public class Main 
{
    public static void main( String[] args )
    {
        System.out.println("Avvio applicazione: Main invocato");
        AbstractApplicationContext applicationContext = new ClassPathXmlApplicationContext(
                "ApplicationContext.xml");

        BeanFactory ai = applicationContext.getBean("beanFactory", BeanFactory.class);


    }
}

A (B bean 相同)

public class A {

    private String name;

    public A(){

    }

    @SuppressWarnings("restriction")
    @PostConstruct
    public void init(){
        System.out.println("Bean A created, name: " + name);
    }

    public String getName(){
        return this.name;
    }

    public void setName(String name){
        this.name = name;
    }   

}

BeanFactory

public class BeanFactory {

    @Autowired
    @Qualifier(value="a1")
    private A a;

    public void setA(A a){
        this.a = a;
    }

    public void printAName(){
        System.out.println("Classe AInstantiator: AInstantiator.printAName -> a.getName() = " + a.getName());
    }

}

这是运行的结果:

Avvio applicazione: Main invocato
Bean A created, name: I am A one!
Bean A created, nome: I am A two!
Bean B created, name: I am B!

怎么可能？!

1) 为什么要创建两个？我在 @Qualifier a1 bean 中指定，而不是两者!限定符注释不是用来绑定(bind)同一类的特定bean吗？对吗？

2) 为什么要创建Bean B？我不将它与@Autowired 绑定(bind)。

如果我删除

 @Autowired 
 @Qualifier(value="a1")

来自BeanFactory，结果是一样的!这不可能。。我不明白。也许编译器崩溃了？请帮忙!

Answer 1

默认情况下，bean 会立即初始化，这意味着容器 "eagerly create and configure all singleton beans as part of the initialization process" 。简单地说，无论是否有任何 Autowiring 或其他依赖项注入(inject)，@PostConstruct 方法都会在启动时调用。

如果您想要其他方式，您需要设置:

lazy-init="true"